On Fri, Oct 5, 2018 at 1:43 PM H.J. Lu <hjl.to...@gmail.com> wrote:
>
> On Sat, Sep 29, 2018 at 11:02 AM Uros Bizjak <ubiz...@gmail.com> wrote:
> >
> > On Sat, Sep 29, 2018 at 6:36 PM H.J. Lu <hjl.to...@gmail.com> wrote:
> > >
> > > When passing and returning BLKmode values in 2 integer registers, use
> > > 1 TImode register instead of 2 DImode registers. Otherwise, V1TImode
> > > may be used to move and store such BLKmode values, which prevent RTL
> > > optimizations.
> > >
> > > Tested on x86-64. OK for trunk?
> > >
> > > Thanks.
> > >
> > > H.J.
> > > ---
> > > gcc/
> > >
> > > PR target/87370
> > > * config/i386/i386.c (construct_container): Use TImode for
> > > BLKmode values in 2 integer registers.
> > >
> > > gcc/testsuite/
> > >
> > > PR target/87370
> > > * gcc.target/i386/pr87370.c: New test.
> >
> > OK.
>
> I'd like to backport it to release branches. Is that OK?
This is a minor optimization bug, not a wrong-code bug, so unless the
patch is super-safe, I think we should leave release branches
unpatched.
Uros
> Thanks.
>
> H.J.
> > Thanks,
> > Uros.
> >
> > > ---
> > > gcc/config/i386/i386.c | 17 +++++++++--
> > > gcc/testsuite/gcc.target/i386/pr87370.c | 39 +++++++++++++++++++++++++
> > > 2 files changed, 54 insertions(+), 2 deletions(-)
> > > create mode 100644 gcc/testsuite/gcc.target/i386/pr87370.c
> > >
> > > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> > > index 176cce521b7..54752513076 100644
> > > --- a/gcc/config/i386/i386.c
> > > +++ b/gcc/config/i386/i386.c
> > > @@ -7914,9 +7914,22 @@ construct_container (machine_mode mode,
> > > machine_mode orig_mode,
> > > if (n == 2
> > > && regclass[0] == X86_64_INTEGER_CLASS
> > > && regclass[1] == X86_64_INTEGER_CLASS
> > > - && (mode == CDImode || mode == TImode)
> > > + && (mode == CDImode || mode == TImode || mode == BLKmode)
> > > && intreg[0] + 1 == intreg[1])
> > > - return gen_rtx_REG (mode, intreg[0]);
> > > + {
> > > + if (mode == BLKmode)
> > > + {
> > > + /* Use TImode for BLKmode values in 2 integer registers. */
> > > + exp[0] = gen_rtx_EXPR_LIST (VOIDmode,
> > > + gen_rtx_REG (TImode, intreg[0]),
> > > + GEN_INT (0));
> > > + ret = gen_rtx_PARALLEL (mode, rtvec_alloc (1));
> > > + XVECEXP (ret, 0, 0) = exp[0];
> > > + return ret;
> > > + }
> > > + else
> > > + return gen_rtx_REG (mode, intreg[0]);
> > > + }
> > >
> > > /* Otherwise figure out the entries of the PARALLEL. */
> > > for (i = 0; i < n; i++)
> > > diff --git a/gcc/testsuite/gcc.target/i386/pr87370.c
> > > b/gcc/testsuite/gcc.target/i386/pr87370.c
> > > new file mode 100644
> > > index 00000000000..c7b6295a33b
> > > --- /dev/null
> > > +++ b/gcc/testsuite/gcc.target/i386/pr87370.c
> > > @@ -0,0 +1,39 @@
> > > +/* { dg-do compile { target { ! ia32 } } } */
> > > +/* { dg-options "-O2" } */
> > > +
> > > +struct A
> > > +{
> > > + int b[4];
> > > +};
> > > +struct B
> > > +{
> > > + char a[12];
> > > + int b;
> > > +};
> > > +struct C
> > > +{
> > > + char a[16];
> > > +};
> > > +
> > > +struct A
> > > +f1 (void)
> > > +{
> > > + struct A x = {};
> > > + return x;
> > > +}
> > > +
> > > +struct B
> > > +f2 (void)
> > > +{
> > > + struct B x = {};
> > > + return x;
> > > +}
> > > +
> > > +struct C
> > > +f3 (void)
> > > +{
> > > + struct C x = {};
> > > + return x;
> > > +}
> > > +
> > > +/* { dg-final { scan-assembler-not "xmm" } } */
> > > --
> > > 2.17.1
> > >
